1. Field of the Invention
The invention relates to networks, particularly those having a plurality of nodes where information is transmitted between the nodes.
2. Prior art
In U.S. Pat. No. 4,918,690 a network is described which includes a plurality of nodes. Each node includes a cell having a unique identification number. The network is initialized through use of the identification numbers of the cells and then a protocol is established so that the cells may communicate among one another over a medium such as a power line, twisted pair, coaxial cable, etc.
In some cases the cells are in different branches of the network and transmission of a high frequency data signal from one cell to another is not always successfully completed through the medium/media. For instance, some cells may be connected to one phase of a power line while other cells are connected to another phase of the power line. High frequency communications between these lines may not be practical because of the impedance to the high frequency signal found in a power network. A power line communications coupler for solving this problem for some applications is described in U.S. Pat. No. 5,192,231. A problem with this coupler is that it requires a direct connection to each of the branches, phases, or the like of the medium/media.
Sometimes it is not convenient to obtain communications signals from the network. For instance, identification numbers (IDs) for nodes needed to initialize the network may be difficult to obtain from each node, because for example, each node is not addressable until its ID is initially determined. As will be seen, the present invention provides a mechanism for obtaining signals from the networks such as the IDs without physically connecting into the network.
In a network having a first and a second branch, a method for coupling a signal from the first branch to the second branch is disclosed. A radio signal propagated from the first branch of the network is sensed. This signal is coupled to the second branch of the network by an electrical connection to the second branch. Thus, the unintended radio frequency transmission of a signal is sensed and put to use.
In one embodiment of the present invention the network nodes are separately caused to transmit their IDs onto the network. These IDs are sensed by a radio frequency receiver and tabulated. Then this tabulated information is transmitted onto the network to allow, for instance, a gateway node to initialize the network.